February 23rd, 2021

лошадь, диаграмма, Фейнман

Нейтрино в астрофизике и космологии: лекции TASI

Neutrinos in Astrophysics and Cosmology: Theoretical Advanced Study Institute (TASI) 2020 Lectures^ https://arxiv.org/abs/2102.10183
Kevork N. Abazajian
I introduce the consequences of neutrino mass and mixing in the dense environments of the early Universe and in astrophysical environments. Thermal and matter effects are reviewed in the context of a two-neutrino formalism, with methods of extension to multiple neutrinos. The observed large neutrino mixing angles place the strongest constraint on cosmological lepton (or neutrino) asymmetries, while new sterile neutrinos provide a wealth of possible new physics, including lepton asymmetry generation as well as candidates for dark matter. I also review cosmic microwave background and large-scale structure constraints on neutrino mass and energy density. Lastly, I review how X-ray astronomy has become a branch of neutrino physics in searches for keV-scale sterile neutrino dark matter radiative decay.
Comments: Theoretical Advanced Study Institute (TASI) 2020 Lectures Chapter; 45 pages, 17 figures
лошадь, диаграмма, Фейнман

Аналитический спектр нелинейного томсоновского рассеяния с учетом реакции излучения

Analytical Spectrum of Nonlinear Thomson Scattering Including Radiation Reaction: https://arxiv.org/abs/2102.11260
A. Di Piazza, G. Audagnotto
Accelerated charges emit electromagnetic radiation and the consequent energy-momentum loss alters their trajectory. This phenomenon is known as radiation reaction and the Landau-Lifshitz (LL) equation is the classical equation of motion of the electron, which takes into account self-consistently radiation-reaction effects in the electron trajectory. By using the analytical solution of the LL equation in an arbitrary plane wave, we compute the analytical expression of the classical emission spectrum via nonlinear Thomson scattering including radiation-reaction effects. Both the angularly-resolved energy spectrum and the angularly-integrated light-cone energy spectrum are reported, which represent the exact classical expressions of the spectra in the sense that neglected contributions are smaller than quantum effects. In this way, we have also obtained a phase-dependent expression of the electron dressed mass including radiation-reaction effects. Finally, the corresponding spectra within the locally-constant field approximation have been derived.
Comments: 14 pages, no figures
лошадь, диаграмма, Фейнман

Самая маленькая жидкость на земле

The smallest fluid on earth: https://arxiv.org/abs/2102.11189
Björn Schenke
High energy heavy ion collisions create quark gluon plasmas that behave like almost perfect fluids. Very similar features to those that led to this insight have also been observed in experimental data from collisions of small systems, involving protons or other light nuclei. We describe recent developments aimed at understanding whether, and if so how, systems that produce relatively few particles (orders of magnitude less than in typical heavy ion collisions) and are only one to a few times the size of a proton, can behave like fluids. This involves a deeper understanding of fluid dynamics and its applicability, improvements of our understanding of the initial geometry of the collisions by considering fluctuations of the proton shape, as well as advancements in the calculation of initial state effects within an effective theory of quantum chromodynamics, which can affect the observables that are used to study fluid behavior. We further address open questions and discuss future directions.
Comments: 28 pages, 6 figures

Апдейт: буквально через пару дней появилось вот что: https://physics.aps.org/articles/v14/27
лошадь, диаграмма, Фейнман

Холодные атомы за пределами атомной физики

Много всякого, в том числе мои любимые амплитуды рассеяния.

Cold atoms beyond atomic physics: https://arxiv.org/abs/2102.10385
Lucas Madeira, Vanderlei S. Bagnato
In the last 25 years, much progress has been made producing and controlling Bose-Einstein condensates (BECs) and degenerate Fermi gases. The advances in trapping, cooling and tuning the interparticle interactions in these cold atom systems lead to an unprecedented amount of control that one can exert over them. This work aims to show that knowledge acquired studying cold atom systems can be applied to other fields that share similarities and analogies with them, provided that the differences are also known and taken into account. We focus on two specific fields, nuclear physics and statistical optics. The nuclear physics discussion occurs with the BCS-BEC crossover in mind, in which we compare cold Fermi gases with nuclear and neutron matter and nuclei. We connect BECs and atom lasers through both systems' matter-wave character for the analogy with statistical optics. Finally, we present some challenges that, if solved, would increase our understanding of cold atom systems and, thus, the related areas.
Comments: 11 pages, 3 figures
лошадь, диаграмма, Фейнман

По-моему, тут ничего нового нет, но методически может быть полезно, пусть будет

A novel method to calculate the electric field using solid angles
Fulin Zuo
A new method to calculate the electric field inside a spherical shell with surface charge in terms of solid angle is presented. The integral can be readily carried out without invoking special functions typically used for this classical problem. For a flat surface of uniform charge density, the electric field normal to the surface is shown to be proportional to the solid angle subtended by the surface only.
ФТФ, ХГУ

"Ускоритель тяжелых ионов": диптих превращается в триптих

В мае месяце прошедшего года (как давно это было!) я опубликовал пару рисунков из задуманной серии "Няшный университет", повествующих о суровых буднях ускорения и столкновения тяжелых ионов:)) И обмолвился, что нужно бы нарисовать и третью часть, изображающую детектирование продуктов реакции. О своем невинном увлечении я упомянул в разговоре со своим однокурсником и другом Шурой Исуповым из Дубны (который, в отличие от меня, окончил художественную школу). Идея оказалась настолько резонирующей, что он отряхнул пыль со своих акварельных красок (к которым не прикасался со студенческих лет) и выдал свое видение третьей части!

В этом посте я опубликую все три части, прошу любить и жаловать! Большое спасибо глубокоуважаемой dsgtq_qfle за сборку рисунка из скана отдельных кусочков!


2019-06-08-colored_smart_blur_50 © qedqed.iMGSRC.RU



2020-05-22-final_corr3_50.jpg © qedqed.iMGSRC.RU



Scan.jpg © qedqed.iMGSRC.RU


Сам я когда-нибудь постараюсь вернуться к этой теме и представить свое видение детектора:))